Amazing. The Cambrian truly is a fascinating period, especially because of the uniquely rich fossil record we have of it. These kinds of soft-body-preserving deposits are all over the world - Canada's Burgess Shale being the most famous, but there are several in China plus at least one in Utah - yet they all cover approximately the same time period. Deposits for later time periods almost never have the same amazing level of detail; it's speculated that burrowing creatures who disturb the carefully preserved clay hadn't evolved yet in the Cambrian.

The Edicarian period before it is still very mysterious, but from what we've seen it has nothing like the complex ecosystems that suddenly appear in the Cambrian. And before that? Just algae and microbes going back billions of years. It's an almost suspiciously fortunate circumstance that the period with the best fossil preservation is this unique turning point in the prehistory of life on Earth.

I am excited to see what new things we learn about the shared species between this site and the previously known sites. It's likely that can even shed some light on the species not found here.

I wonder if the originating sediment was especially rich in clay particles. In addition to the lack of metamorphosing of the rock through heat or pressure, the size of particles in the sediment is important for preserving details. Clay particles tend to be the smallest and thus may do the most to preserve the finest features.

"Part of this issue is that those fossils are rare, as many rocks of that period appear to have been wiped off the Earth by a globe-spanning glaciation"

How do fossils that were clearly buried very quickly be preserved by a process that takes so long? I have a hard time believing an extremely slow process of "glaciation" would create footprint fossils. More like a global flood where features are buried very quickly.

"Part of this issue is that those fossils are rare, as many rocks of that period appear to have been wiped off the Earth by a globe-spanning glaciation"

How do fossils that were clearly buried very quickly be preserved by a process that takes so long? I have a hard time believing an extremely slow process of "glaciation" would create footprint fossils. More like a global flood where features are buried very quickly.

The *rocks* (and the fossils they may have contained) were wiped out by glaciation, not the animals. Glaciers are great for turning rocks into gravel.

"Part of this issue is that those fossils are rare, as many rocks of that period appear to have been wiped off the Earth by a globe-spanning glaciation"

How do fossils that were clearly buried very quickly be preserved by a process that takes so long? I have a hard time believing an extremely slow process of "glaciation" would create footprint fossils. More like a global flood where features are buried very quickly.

Glaciation didn't create the fossils. Glaciation wiped away the other fossils that were created at the same time.

And since there is absolutely no evidence for a global flood, it is impossible for one to have made fossils.

Amazing. The Cambrian truly is a fascinating period, especially because of the uniquely rich fossil record we have of it. These kinds of soft-body-preserving deposits are all over the world - Canada's Burgess Shale being the most famous, but there are several in China plus at least one in Utah - yet they all cover approximately the same time period. Deposits for later time periods almost never have the same amazing level of detail; it's speculated that burrowing creatures who disturb the carefully preserved clay hadn't evolved yet in the Cambrian.

The Edicarian period before it is still very mysterious, but from what we've seen it has nothing like the complex ecosystems that suddenly appear in the Cambrian. And before that? Just algae and microbes going back billions of years. It's an almost suspiciously fortunate circumstance that the period with the best fossil preservation is this unique turning point in the prehistory of life on Earth.

I am excited to see what new things we learn about the shared species between this site and the previously known sites. It's likely that can even shed some light on the species not found here.

One of my all-time favorite science books is Stephen Jay Gould's "Wonderful Life", which is about the discovery of the Burgess Shale. While some of the information is outdated and/or controversial, Gould writes with a sense of wonder and discovery that is rare in science literature.

"Part of this issue is that those fossils are rare, as many rocks of that period appear to have been wiped off the Earth by a globe-spanning glaciation"

How do fossils that were clearly buried very quickly be preserved by a process that takes so long? I have a hard time believing an extremely slow process of "glaciation" would create footprint fossils. More like a global flood where features are buried very quickly.

Glaciers don't create fossils, they result in fossils that "have been wiped off the Earth". That's because they tend to drag rocks, essentially scraping away fine detail.

You're right that fossils form better when they are buried, e.g. by sediment, and then that sediment becomes sedimentary rock over time. But flooding is not a factor here because these are marine organisms, they were already underwater during life.

A lot of these changes have been hinted at from things like cladistic studies. For example, cladistics suggests the common ancestor of all trilobites (ie. the first trilobite) must have been something like 30Ma (this is from memory) before the first known trilobite fossil - ie. well into the Ediacaran.

"Part of this issue is that those fossils are rare, as many rocks of that period appear to have been wiped off the Earth by a globe-spanning glaciation"

How do fossils that were clearly buried very quickly be preserved by a process that takes so long? I have a hard time believing an extremely slow process of "glaciation" would create footprint fossils. More like a global flood where features are buried very quickly.

I have incredible respect for paleontologists. They spend some grueling time in the field, often in some inhospitable places, and if they even find fossils, the painstaking detail work of removing the fossil safely, transporting it back to the lab, and then carefully remove a lot of the surrounding rock. I will freely admit that I don't have that kind of patience. The fossils the eventually present to us are precious gifts from the unimaginably distant past, showcasing worlds that we might find familiar in a sci-fi book. Keep up the excellent work!

"Part of this issue is that those fossils are rare, as many rocks of that period appear to have been wiped off the Earth by a globe-spanning glaciation"

How do fossils that were clearly buried very quickly be preserved by a process that takes so long? I have a hard time believing an extremely slow process of "glaciation" would create footprint fossils. More like a global flood where features are buried very quickly.

Glaciation didn't create the fossils. Glaciation wiped away the other fossils that were created at the same time.

And since there is absolutely no evidence for a global flood, it is impossible for one to have made fossils.

But aren't glaciers ice? Which is water? So a global glaciation is really just a flood with very hard water!

"Part of this issue is that those fossils are rare, as many rocks of that period appear to have been wiped off the Earth by a globe-spanning glaciation"

How do fossils that were clearly buried very quickly be preserved by a process that takes so long? I have a hard time believing an extremely slow process of "glaciation" would create footprint fossils. More like a global flood where features are buried very quickly.

Glaciation didn't create the fossils. Glaciation wiped away the other fossils that were created at the same time.

And since there is absolutely no evidence for a global flood, it is impossible for one to have made fossils.

But aren't glaciers ice? Which is water? So a global glaciation is really just a flood with very hard water!

My understanding is most of what we know of the Cambrian is from the Burgess Shale. This give a look at species half a world away.

I’m having trouble figuring out the relative locations of South China and the BC Rockies at the time. Some sources indicate they’d have been neighbours in Laurasia, others indicate they’d have been far apart.

My understanding is most of what we know of the Cambrian is from the Burgess Shale. This give a look at species half a world away.

I’m having trouble figuring out the relative locations of South China and the BC Rockies at the time. Some sources indicate they’d have been neighbours in Laurasia, others indicate they’d have been far apart.

It depends on when you are in the Cambrian; it does cover some 55.6 million years after all! At the start, the supercontinent of Pannotia was in the Southern hemisphere. By the end, Pannotia had broken up into Gondwana, Laurentia, Siberia, and Baltica and moved quite a bit. As a result, both sources could be correct.

The Edicarian period before it is still very mysterious, but from what we've seen it has nothing like the complex ecosystems that suddenly appear in the Cambrian. And before that? Just algae and microbes going back billions of years. It's an almost suspiciously fortunate circumstance that the period with the best fossil preservation is this unique turning point in the prehistory of life on Earth.

Your comment provides a real nice walk trough of the context, but this is arguable. The later comment of winwaed references ecological studies that links the last 1/3 of the Edicarian assemblages - the Avalon explosion 575 Ma - to the early Cambrian explosion. Of them Dickinsonia is now considered an animal [ https://www.nature.com/articles/d41586-018-06767-6 ]. And arguably the Avalon Petalonamids may tree them nicely:

Added to that there are ongoing analysis (i.e. debate) how species diversification and later sampling works out to possibly bias or not the apparent "explosions" at various places in the fossil record. (But that area is so large that I won't even try to reference it; I need a good recent review article on it.)

"Part of this issue is that those fossils are rare, as many rocks of that period appear to have been wiped off the Earth by a globe-spanning glaciation"

How do fossils that were clearly buried very quickly be preserved by a process that takes so long? I have a hard time believing an extremely slow process of "glaciation" would create footprint fossils. More like a global flood where features are buried very quickly.

Glaciation didn't create the fossils. Glaciation wiped away the other fossils that were created at the same time.

And since there is absolutely no evidence for a global flood, it is impossible for one to have made fossils.

What buried these creatures so quickly and preserved them for thousands of years? A massive flood would do that. No one has proved it didn’t happen and many ancient cultures recorded stories of a flood that wiped out mankind. The resistance to such a flood explanation is not based on science, just prejudice. It fits the evidence.

What buried these creatures so quickly and preserved them for thousands of years? A massive flood would do that. No one has proved it didn’t happen and many ancient cultures recorded stories of a flood that wiped out mankind. The resistance to such a flood explanation is not based on science, just prejudice. It fits the evidence.

And we don't have to prove that a flood didn't happen; you have to provide evidence that a flood did happen. As noted previously, there is no evidence for a global flood. If you think you have some, then please bring it forward. (Just remember - folklore is not evidence and the Cambrian happened about 485,400,000 years ago.)

I just refreshed my feed, and AFAIU Chengjiang is playing "Who's on first" with Qingjiang:

Quote:

Even without formal descriptions of the new species, the fossils are answering questions. Ctenophores, also called comb jellies, are one of the earliest branches of the animal evolutionary tree. In their present form, they have tentacles, but there had been no early fossil with these appendages, leading to the suggestion that they evolved relatively recently. But there's a fully tentacled comb jelly in Qingjiang, so that debate appears to be over.

From a Chengjiang locale, I think:

"Now an international team of palaeontologists have found fossil evidence that proves comb jellies are related to ancestors that sat on the sea floor with polyp-like tentacles.

As reported today in Current Biology, researchers from the University of Bristol, Yunnan University in China and London's Natural History Museum, compared a 520 million-year-old fossil with fossils of a similar skeletal structure and found that all evolved from the same ancestors.

The fossil, set in a yellow and olive coloured mudstone and resembling a flower, was found in outcrops south of Kunming in the Yunnan Province, South China by Professor Hou Xianguang, co-author of the study."

"The researchers noticed that Daihua resembled another fossil, a famous weird wonder from the Burgess Shale (508 million years old) called Dinomischus. This stalked creature also had 18 tentacles and an organic skeleton and was previously assigned to a group called entoprocts.

"We also realised that a fossil, Xianguangia, that we always thought was a sea anemone is actually part of the comb jelly branch," said co-author Prof Cong Peiyun.

This emerging pattern led researchers to see a perfect transition from their fossils all the way up to comb jellies."

""With such body transformations, I think we have some of the answers to understand why comb jellies are so hard to figure out. It explains why they have lost so many genes and possess a morphology that we see in other animals," added co-author Dr Luke Parry.

Until around 150 years ago, zoologists had considered comb jellies and cnidarians to be related. This theory was challenged more recently by new genetic information suggesting comb jellies could be a distant relative to all living animals below the very simple looking sponges.

The authors of this new study believe their findings make a strong case for repositioning the comb jelly back alongside corals, sea anemones and jellyfish."

Figure 7Body Plan Evolution and Homology among Stem CtenophoresTop: the evolution of the tentacle-ctene ciliary organ in coelenterates. While being simple in Cnidaria, the dinomischids evolved rows of compound cilia, either set on pinnules in the early diverging forms or as a ribbon-shaped tentacle with transverse rows of cilia over a cushion plate structure in Siphusauctum. As in the sessile stem-group ctenophores, the scleroctenophores (Galeactena) exhibit paired ciliary rows on their tentacle-ctene ciliary organs. Only crown-group ctenophores and the Burgess Shale forms exhibit fused ctenes evidenced by the underlying nerve.

Bottom: the relative proportions and association of the major body compartments and their homology with the cnidarian outgroup. The main body compartment is the columnar body in polypoid cnidarians, while this is present as the mesentery bearing calyx in stem-group ctenophores. The oral surface becomes expanded in more derived stem groups, while the calyx becomes reduced into the small region harboring the apical organ in crown-group and Burgess Shale ctenophores.

Bayesian phylogenetic analysis using the mki + gamma model on a dataset containing 278 characters and 90 living and fossil taxa. Numbers at the nodes are posterior probabilities, and the scale bar is in units of the expected number of substitutions per site. The dataset is expanded and modified from previous datasets [2, 11, 13, 53] to include “dinomischids,” which form a paraphyletic grade on the ctenophore stem. See also Methods S1 and Figure S7 for additional analyses using other optimality criteria.

This is especially nice since the genetic debate has been long and ardous, and it was just recently that more comprehensive and robust sequence data and methods that better described rate change variation in the genome started to reveal the most likely species tree.

"Improved Modeling of Compositional Heterogeneity Supports Sponges as Sister to All Other Animals"

"The relationships at the root of the animal tree depend on model adequacy, with Ctenophora-sister emerging more prominently when the data are modeled less adequately and Porifera-sister being better supported when the data are more adequately modeled (Figure 1). "

"In addition, Porifera-sister has been corroborated by analyses of presence/absence of orthologous genes [6], whereas Ctenophora-sister is currently uncorroborated by independent evidence."